Rotary milling tool



Nov. 20, 1945 w. c. HARRISON ROTARY MILLING TOOL ZSheets-Sheet. 1

Filed NOV. 8, 1944 Nov. 20, 1945. w. c. HARRISON 2,389,235

ROTARY MILLING TOOL Filed Nov. 8, 1944 2 She ets-Sheet 2 if j E I WWW/am '6. 1762777 90 Patented Nov. 20, 1945 S PATENT OF FICE ROTARY MILLING TOOL William C. Harrison, Rapid City, S. Dak.

Application November 8, 1944, Serial No. 562,509

5 Claims.

This invention relates to milling cutters f the rotary type for cutting and reaming bored open ings in pieces of work and the interior areas of tube sections, It is adaptable for tools of this character in general in machine shop practice but is primarily intended and has to do with the cutting and reaming of the interiors of tube sections in oil Well installation and the like.

Heretofore, the usual practice has been to use a cutting and reaming tool having a single cutter element'or single series of the same, which necessitates withdrawal of the tool from the well tubing each time it is necessary to replace the dulled cutting tool or the cutting element thereof. This not only involves considerable loss of time but is expensive. l

The prime object of the invention is to minimize the cost and operation of such a tool and consists essentially in the provision of a multiplicity of cutting elements arranged and adapted to be brought successively into operating position, at will, after one of the cutting members of the series or a particular cooperative set thereof has become dull,

An illustrative but non-limiting adaptation of the invention is illustrated in the accompanying drawings, in which: 7

Figure 1 is a side elevation of the entire tool assembly;

Figure 2 is a view on an enlarged scale, partly in longitudinal section and partly in side elevation, with intermediate portions broken away to foreshorten the view;

Figure 3 is a detailed sectional view of a portion of the tool in the immediate region of the longitudinal series of cutter elements;

Figure 4 is a cross sectionlon the line 44 of Figure 3;

Figure 5 is a section on the line 55 of Figure 3' Figure 6 is a detail perspective View of one of the ejector springs detached; and Figure 7 is a detail perspective view of one of the cutter elements detached.

Referring now to the drawings in detail, the

tion terminating adjacent the lower end of the tubing at the point designated by the transverse dotted line IS in Figure 1 and shown structurally in Figure 2. The lower end of the casing I0 is closedby a plug member l6 (see Figure 2).

Slidable longitudinally in the casing I0 is a plunger element ll. Externally, the plunger elev ment I! is of polygonal form corresponding to the polygonal portion of the tube II], A part of the upper end portion of the plunger I1 is formed cylindrically, as at l8, thereby providing a piston head which works in the cylindrical upper portion of the tubing 10. With the plunger ll thus formed, its polygonal portion slides longitudinally in the counterpart portion of the tube In Without turning, movement of the plunger in one direction being under the influence of fluid pressure admitted through the bore l3 of the cylinder head 12 and against the piston portion l8. Reverse travel of the piston is effected by reaction of a spring element l9 which is compressed during the downward travel of the plunger under fluid pressure above the piston head I8. The spring element l9, which is of considerable length, has its upper portion contained within an internal axial bore in the plunger, as atlll (see Figure 3), while the lower end of the spring abuts the plug 16 at the bottom of the casing in (see Figure 2). i

The plunger ll is recessed or grooved longitudinally in one or more of its'polygonal vfaces, as

numeral Ill designates generally the tubular outer casingf'of the tool of the present invention. Bolted annularly, as at l I, to the upper end of the'tubular casing i0 is a pressure head l2 having a screw threaded axia'l bore l3 therein for the attachment of a tubular operating stem (not shown) by which the ,tool is lowered into the well bore for operation, The interior of the tubular casing in is cylindrical from the head I2 throughout a' considerable'distance therefrom at 2|, in which a series of cutter elements 22 are hingedly mounted on transverse pins or bolts 23. The elements 22 are of thickness corresponding substantially to the distance between the bottom of the groove and opposed adjacent face of the tubing Ill. In the normal, folded in position of the cutter elements 22, the plunger l 'l is slidable freely lengthwise of the tubing 10. interposed between the bottom of the groove 2| and adjacent inner face portions of the cutter elements 22 are substantially V-shaped ejector springs 24, said springs 24 when compressed being received in depressions 25 provided therefor in the bottom of the groove 2!. At one end of each spring 24 is an outturned lug 26 whichis received loosely in a cavity provided therefor in the cutter element 22, and at the opposite end of the spring is a corresponding lug 21 that is received in a notch 28 formed in the bottom of the recess 25. The

spring members 22! being compressed in the folded in position of the cutter elements 22, and

thus placed under tension, react to press the cutc outwardly on its pivot 23, the other corner por tion being angular so as to provide a. square shoulder 31 which abuts the bottom of the groove 2| and limits the outturned position of the ele& ment 22 to a right angular or perpendicular positiomas-shownin Figured Thelongitudinahopenings29'in the casing Iii a'ref cach of a lengt'h to permit thecutterelement- 2 2to-swing out therethroug'h as-the element 22 is brought into" registration therewith and under the" infiuence-ofthe spring element 24; which lat a ter; after the cutter element '22 has moved approximately: to its'full open= position, is released f'rom'its engagement with the cutter element and therecess28, and drops intothe space below in the lon'gitudinal groove 2| of the plunger H. To minimize the length of the opening 2?! and facilitate-the= opening or the" cutter element 22, the upperend portion'of the opening 2-9" is beveled off; asa t 32. Tofurtherfacilitatethe opening of the cutter element22 the freeend portion of theelementis'undercuti arcuately; as at 33, this form of 'the' end portion of the cutter element serving tc de'fiect the element outwardly with" a camefiect as the same" engages and rides on the lower ends-f the opening 2-9:

The'fre'e end portion of the-cutter element 22 is also roundedofi in'toppla-n; as at 3t, thus pro-- ducing a sharp cornerii at theleading side of tll'e element. The cutter element 22i's" further undercut; roundingly on its under rear" portion; as'f'at 316i *thusproducing' a longitudinal cutting edge 3:1? atthebottom of the element and along leading-side: In the normal lifted position ofthe' plunger element ll, all ofthe cutter el'e merits" 22-a-re retracted within the tubular" casihl-OE this positionof the plungerelement being governecr'and manntained-- by the spring. element I9. When fluid pressure is exerted on the piston headlSf the plungerelement H is forced downwardly'a'gainstthe reaction of the'spring element i'sjan'd as'the' first set of cutter elements22 ride into-registration withtherespective openings 29 in the casing W, saidel'ement's 22 are forced out wardly'throu'gh the openings 29' and into cutting position; asishown in the illustrated position of thecutters'of thesec'ondseries; Figure 3; When the projected cutter element 22 has become dulle'din the use" thereof, and while the tool is kept'in' the Working position in which the dull cutter element 22'has been. operating, the plunger element flfis relieved of the fluid pressure thereabove; whereupon the spring element l9 lifts the plunger element and retracts the projected and; dulled cutter element. Thereafter, whenv fluid pressure is again. applied to the plunger element H; the latter is forced downwardly against the tensionof the springelement. I 9; and the cutter element or elements 22 which have become: dull and now have no spring elements 24 behind'them,

the same ride downwardly past the opening 29 in the casing 10, but the next succeeding sharpened cutter element 22 is forced outwardly through the opening 29 by its confined spring element 24 as th cutter element rides into registration with the opening 29. Then, as with the preceding cutter elements 22 which have been used and become dulled, the spring element 24 becomes disengaged from this last projected cutter element and the recess 28 of the' plunger element and dropsinto'the space below in the groove 2!.

Normally, the used and dulled cutter elements 22 being free of the-action of any spring elements 2 1; said, cutter elements will ride past the openi'ng 25f. This is because said used elements hang vertically by: gravity, but to assure passage of the lower. end portion of the cutter elements past the bottom endof the opening 29, said end portionrisibeveled off, as at 38, to provide an inwardly and downwardly inclined cam surface and eliminate any abrupt shoulder to obstruct the travel of" the'cutter' element" 22- should the latter swing slightly outward" but not to the outside of the casing I 0. 2

From: the foregoing description of the illustrative structural exemplification of the invention, apractical and eflioient rotary tool isproduced for cutting and-reamingborespieces of work and the sameis-"particularly advantageous-for use in-the cutting and reaming of" tubing in; oilwell' installations and the like: The illustrated struc ture' is but on -practical embodiment of the in:- vention: Considerable'modification of the'strueture'i s' contemplated within the purview of the invention" as definedi'rr the appended claims, and the invention, therefore, is not limited" to its specific construction" and arrangement shown.

Having thus described the invention, what" is claimedis:-'

LA rotary milling tool of the character'de scribed; thesa-me comprising' a" tubular body casing; said casinghaving a longitudinal opening in the wall thereof; a' plunger element slidably mounted longitudinally in said body casing but, held against rotation, therein; means? for yielda-b'ly holding said plunger element in a. normal raised position and for restoring saidelement to" such position; andmeans for moving said plunger element downwardly insaid bodycasing against the action" of said means for upward movement of said plunger element, a; longitudinal series of cutter elementsmovably mounted on said plunger element said cutter elements, being held. normally within said". h'ody, casing in the normal raised position. of said" plunger. element,

I meansv interposed betweensaid" plunger element andthe respective cutter elements, for projecting said cutter. elements outwardly through'the. lo'ngitudinal opening in the body casing; when said cutter elements are successively brought intoregistra'tion with said opening or: the, casing, thesuccessive projection of the cutter elements being effected intermittently after. an intermittent" retraction of preceding cutter" elements; that. have been?nmlectetLjuSEd;and'lo ecome. dull.

22A rotary, millingvtiool'structur'e asset forth in claim 1,; the projctihgmeansfr the cutter elementsto mp'risinga. detachable sprin element interposed betweemeach cutter? element. and the plunger; element ofth'e-tool, said spring element being compressed in the; normal position 05 the cutter .elementand}.1 -.eactingto. project the outter element. an extended cutting. positionthrough the opening .ihr the. body casing, as, the, plunger element is moved't'o bring the cutting element into registration with said opening, said spring element, after projection of the cutter element, becoming disengaged from the cutter element and the plunger element and dropping into space within the body casing below the projected cutter element.

3. A rotary milling tool of the character described, the same comprising a tubular body casing having a pressure head at the upper end thereof, said pressure head having an axial bore and provision for its attachment to the lower end of a tubular operating stem, pressure fluid being controlled and admitted through said stem and pressure head into t e upper portion of said body casing, the upper portion of the body casin constituting a pressure chamber, an elongated plunger element slidably fitted in said body casing, said plunger element having a piston head at its upper end working in the pressure chamber of said body casing, means for holding the plunger element from rotation but permitting longitudinal reciprocation of the plunger element within the body casing, a spring element interposed between the bottom of the body casing and said plunger element, said spring element holding the plunger element yieldably in a normally raised position and restoring said element to such position, said spring element yielding to downward movement of the plunger element under pressure of the fluid applied thereabove but reacting to lift the plunger element when relieved of the fluid pressure thereon, said plunger element having at least one longitudinal groove therein, a longitudinal series of separate cutter elements hingedly mounted on said plunger element and normally suspended from their respective hinge mountings and located within the groove of the plunger element, detachable spring elements interposed between the respective cutter brought into registration with said opening in the body casing, the respective spring elements becoming detached and disengaged from each cutter element and dropping into the space below the cutter element in said longitudinally grooved portion of the plunger element after the directly associated cutter element is projected through the opening in the body casing.

4. A rotary milling tool as set forth in claim 3, and further specifying more specifically that one corner of the hinged portion of the cutter element is cutaway to permit outward swinging of the element, the opposite corner portion of the element being angular and providing a shoulder to abut the bottom of the longitudinal groove in the plunger element whereby to limit and maintain the projected position of the cutter element, and the working position ofthe cutter element longitudinally of the tool being determined by contact of the underside of the cutter element with the bottom end of the opening in the body casing.

5. A rotary milling tool as set forth in claim 3, and further specifying more specifically that the pressure chamber of the body casing is of cylindrical form, but the remainder of the casing is of polygonal form and the major portion of the plunger element is of a counter-part form and fitted to said polygonal portion of the body casing whereby the plunger element is capable of longitudinal reciprocation within the casing but held from rotation therein.

WILLIAMC. HARRISON. 

